ioctl on perlhost platforms take a char*, not void*

As of commit 0cb9638729 IOCtl from perlhost is prototyped to take a char *.
In the later commit 2986a63f7e5 the netware commit is introduced that adds
a void* cast without explination, but today PerlLIOIOCtl is prototyped as
char* in nwperlhost.h (nwperlhost.h didnt exist at 2986a63f7e5 ). In
commit 6e22d04617 Win32 starts to use the void * cast from netware.

Using a void * cast breaks a VC 2003 C++ mode build of IO.xs because of
different types. Switch to a char * cast that matches the vtable prototype.